107
TROUBLESHOOTING
PB
Description
• Water side heat exchanger antifreeze protection.
• The unit shuts down.
• The error code is displayed on the main PCB and the relative ANTI.FREEZE icon is displayed on the user
interface.
Possible causes
• Normal system protection.
• Temperature sensor not connected properly or has malfunctioned.
• Main PCB is damaged.
PB
↓
Outdoor ambient temperature ≤ 4°C
YES
→
Normal system protection. The system will
automatically resume
NO
↓
Water side exchanger water outlet temperature
sensor, water inlet temperature sensor or backup
electric heat exchanger outlet water temperature
sensor is loose (1)
YES →
Ensure the temperature sensor is connected
properly
NO
↓
Water side exchanger water outlet temperature
sensor, water inlet temperature sensor or backup
electric heat exchanger outlet water temperature
sensor has short-circuited or failed (2)
YES →
Replace the temperature sensor
NO
↓
Replace main PCB
1 Backup electric exchanger water outlet temperature sensor, water side exchanger water outlet temperature
sensor and water side exchanger water outlet temperature sensor connections are port CN6 on the main
PCB.
2 Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not
consistent with the sensor’s resistance characteristics table, the sensor has failed.
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